DC:
Chao imported from SA1 may lost their color if you leave the chao
garden, but the color will still be in their DNA, so, for example,
if you import a Ruby chao from SA1 into SA2 and it loses its color,
when it reincarnates/mates the baby will be Ruby. This is because
SA2 checks every chao to see if it was born in a SA2 Chao, if not,
it will lose its color (but still have a trace of its original color).
When your special chao that has been normalized reincarnates/mates,
the offspring will be the correct color.

GCN:
In Sonic Advance, you can collect special metallic chao. When you
import them to Sonic Adventure 2 Battle, they will keep they're color
and can make special Chao that aren't available for the Dreamcast.

Light
Chao

1. Reincarnate
a chao twice.

2. Feed
it one of every animal (Including Blue, Black, and Orange Animals).

3. Feed
it a Chao Fruit.

4. Wait
for evolution.

Angel
and Devil Chao

Devil
Chao-

1. Have
your chao reincarnate twice.

2. Give
it every animal (Special, Ghost, and Imaginary also),

3. Give
your chao a Dark Fruit 4. Evolve your chao. It should make dracula music
when he/she's finished evolving.

Angel
Chao-

1. Have
your chao reincarnate twice.

2 Give
it every animal (Special, Ghost, and Imaginary also).

3. Give
your chao a Hero fruit. 4. Evolve your chao.

Special
GCN-Only Chao (Require GBA)

Clear Chao - Mate
a Dark Shiny Blue Chao from the GBA with a Normal Hero Ruby Chao. Give
the heart fruit to the Dark Chao, but it is suggested that you give
it to both.